Tissue/towel paper products such as facial tissues, paper towels, bath tissues, napkins and other similar products, are designed to include several important properties. For example, products should have good bulk, good absorbency, a soft feel, and should have good strength and durability. Unfortunately, when steps are taken to increase one property of the product, the other characteristics of the product are often adversely affected.
Formulators have for years attempted to balance the level of softwood fibers in their paper structures to ensure adequate strength of their structures while at the same time trying to minimize the negative impact on softness, durability or absorbency generally resulting from higher levels of softwood fibers. One example of the problem has been that formulators of bath tissue products have been unable to reliably make acceptable fibrous structures, for example multi-density structures such as that made by, but not limited to, the through-air-dried (“TAD”) processes, Advanced tissue making process (ATMOS)™ by Voith, New tissue making technology (NTT)™ by Valmet, the Valmet QRT process, the eTAD process from Georgia Pacific, the Andritz textured tissue process (TEX) and other similar processes that create distinct sheet density differences that can contain 20% or less by weight softwood fibers on a dry fiber basis without requiring excessive refining of the softwood/hardwood fibers and/or adding excessive chemical strength agents to achieve the desired level of strength and/or reliability (avoid sheet breaks during making and/or processing).
Similarly, creating multi density structures for paper toweling products, formulators work to develop new products that have higher in-use strength (wet strength) at lower or equal dry strength. However, as formulators use typical paper making process variables to increase product in-use or wet strength, other consumer desired attributes such as absorbency and/or softness typically decrease. The typical problem formulators struggle with for paper toweling is how to increase towel in use or wet strength while maintaining or improving softness and/or absorbency, or how to decrease softwood inclusion while maintaining total product strength, absorbency, and/or sheet flexibility. All the normal paper making process variables available to a papermaker for increasing strength, normally can negatively affect the sheet feel and product absorbency.
Accordingly there continues to be a need for new fibrous paper structures that further optimize the physical product performance of tissue and towel products that increase wet and dry strength without sacrificing as much softness, absorbency and paper making reliability. Such structures are especially valuable for multi-density paper making structures with non-limiting examples of such structures being through air dried (TAD), E-TAD, Valmet NTT, Valmet QRT, Voith ATMOS, Andritz TEX, and UCTAD processes.